1. Field of the Invention
The present invention relates to a mount shelf for an electronic circuit board. More particularly, the present invention relates to a mount shelf for an electronic circuit board, which has an excellent air permeability at a condition that an electronic circuit board is positioned and mounted in a body plate and also has an excellent radiation performance with regard to a heat generated by a part of the electronic circuit.
2. Description of the Related Art
As known in Japanese Laid Open Utility Model Application (JU-A-Showa, 64-387) and Japanese Laid Open Patent Application (JP-A-Heisei, 8-23181), an electronic circuit board is assembled in an electronic apparatus, such as a computer and a communication apparatus, and it is mounted in a body plate. The electronic circuit board mounted in a shelf structure requires the protection against heat generated by it. The shelf which is a mount technique for improving the heat radiation performance is known as shown in FIG. 1. The body plate for embodying the known shelf is constituted by a side plate 101, a ceiling plate 102 and a bottom plate 103. Opposite positioning grooves 106, 107 are formed on an upper guide plate 104 and a lower guide plate 105 which are respectively attached to edges of the ceiling plate 102 and the bottom plate 103. An electronic circuit board 108 is positioned in upper and lower edge regions of the positioning grooves 106, 107, and inserted towards the side plate 101. A large number of long holes 109, 110 are made in the ceiling plate 102 and the bottom plate 103. Guide rims 111, 112 are formed in the edges of the long holes 109, 110. Both ends of the rims 111, 112 are cylindrically formed. A tip end of the electronic circuit board 108 is guided between the planes of the cylinders adjacent to each other, and inserted towards the side plate 101.
At that mount position, a connector 113 attached to the electronic circuit board 108 is electrically connected to a connector 114 attached to the side plate 101. The electrically attached parts of the connectors 113, 114 are constituted by minute metallic parts. In order to effectively connect such minute metallic parts, the relatively positional relations must be accurate between the long holes 109, 110 and the positioning grooves 106, 107. The positional relations must be accurate as a three-dimension, as represented by the three-dimensional coordinates in FIG. 1. Actually, the dimensional setting must be relationally accurate between a Z-axis direction distance A between the side plate 101 and the upper and lower guide plates 105, 106, X-axis direction distances B, C from the standard positions of the upper and lower positioning grooves 106, 107 and a Y-axis direction distance D between the upper and lower positioning grooves 106, 107. If such a dimensional setting is not accurate, a travel direction E when the electronic circuit board is inserted is not accurately coincident with the set Z-axis direction. Even if the mount position is approximately accurate, the electrical connection becomes imperfect between the connectors 113, 114. If the unreasonably pushing force at the time of the insertion is excessive, the electrical connection becomes imperfect. Such known structure requires the highly precise design in order to attain the excellently electrical connection. This results in the increase in a manufacturing cost. Moreover, the plates constituting the large number of holes resist the flow of the air flowing from a lower portion to an upper portion. This resistance causes the flow to be deteriorated. Thus, the air flow becomes the turbulent flow, which causes the heat radiation performance to be poor.
The positioning accuracy is desired to be high. In particular, it is desirable that the unreasonably excessive force is not applied at the time of the insertion, the insertion is smooth, and the positioning accuracy is high. Moreover, the heat radiation performance is desired to be high. It is further required to simplify the shelf structure and drop the manufacturing cost.
Japanese Laid Open Patent Application (JP-A-Showa, 59-181692) discloses the following positioning apparatus of printed circuit board. This positioning apparatus of printed circuit board transfers the printed circuit board to a station to perform a operation such as parts mounting. The positioning apparatus of printed circuit board is provided with: a plurality of guide means for guiding right and left end portions of the printed circuit board to the station. One of the plurality of guide means can move in a direction at right angles to a transferring direction of the printed circuit board. The other of the plurality of guide means cannot move. A plurality of positioning pins to be inserted in reference holes of the printed circuit board are provided in the transferring direction at established intervals. A part of the plurality of positioning pins can move only in the direction at right angles to the transferring direction of the printed circuit board. Another part of the plurality of positioning pins can move in both the direction at right angles to the transferring direction of the printed circuit board and the transferring direction.
The present invention is accomplished in view of the above mentioned problems. Therefore, an object of the present invention is to provide a mount shelf for an electronic circuit board, in which a positioning accuracy is high and a cost can be dropped.
Another object of the present invention is to provide a mount shelf for an electronic circuit board, in which an unreasonably excessive force is not applied at a time of an insertion, an insertion is smooth, a positioning accuracy is high, and a cost can be dropped.
Still another object of the present invention is to provide a mount shelf for an electronic circuit board, in which a positioning accuracy is high, a cost can be dropped, and a heat radiation performance is high.
Still another object of the present invention is to provide a mount shelf for an electronic circuit board, in which when a shelf body is made of metal, the abovementioned problems can be effectively solved.
In order to achieve an aspect of the present invention, a mount shelf for an electronic circuit board, includes: a body; a first guide which is supported by the body and has a first guide plane; a second guide which is supported by the body and has a second guide plane; a third guide which is supported by the body and has a third guide plane; and a fourth guide which is supported by the body and has a fourth guide plane, and wherein the first guide plane and the second guide plane respectively have first contact planes on which a first end plane portion of one straight first edge region of an electronic circuit board can be contact at a same time, and wherein the third guide plane and the fourth guide plane respectively have second contact planes on which a second end plane portion of another straight second edge region of the electronic circuit board can be contact at the same time, and wherein the first guide and the second guide are separated to a degree of a width in a direction in which the first edge region or the second edge region of the electronic circuit board is extended and wherein the third guide and the fourth guide are separated to the degree of the width.
In this case, the first contact plane includes two first slants which are located opposite to each other, and slanted in directions opposite to each other, and in forms of substantially circular cone plane, and wherein the second contact plane includes two second slants which are located opposite to each other, and slanted in directions opposite to each other, and in forms of substantially circular cone plane.
Also in this case, the first and second edge regions are approximately parallel to each other.
Further in this case, the first end plane portion contains two first end lines parallel to each other, and the second end plane portion contains two second end lines parallel to each other.
In this case, the first slant and the second slant are both formed in perfectly circular cone planes.
Also in this case, the first guide and the second guide have a first plurality of protrusions respectively aligned in a straight line direction, and wherein the third guide and the fourth guide have a second plurality of protrusions respectively aligned in a straight line direction, and wherein the first plurality of protrusions are respectively constituted by the first slant, and the second plurality of protrusions are respectively constituted by the second slant.
Further in this case, the mount shelf for an electronic circuit board further includes: a first positioning unit integrally formed into the body; and a second positioning unit integrally formed into the body, and wherein the first positioning unit has a first plurality of grooves for guiding the first edge region, and the second positioning unit has a second plurality of grooves for guiding the second edge region, and wherein positions of the first plurality of grooves correspond to positions of a first plurality of valleys between the first plurality of protrusions, respectively, and positions of the second plurality of grooves correspond to positions of a second plurality of valleys between the second plurality of protrusions, respectively.
In this case, a portion between the two first slants is formed in a cylindrical plane, and a portion between the two second slants is formed in the cylindrical plane.
In order to achieve another aspect of the present invention, a mount shelf for an electronic circuit board, includes: a body; and four guides which are supported by the body, and respectively have axis lines parallel to each other, and are extended in directions of axis lines, and wherein each of the four guides has a plurality of concave grooves aligned in the direction of the axis line, and wherein each of the plurality of concave grooves has both sides crossing the axis line and a cylindrical plane for connecting between the both sides, and wherein two the cylindrical planes of the four guides can contact with one edge region of the electronic circuit board at a same time, and the other two cylindrical planes of the four guides can contact with another edge region of the electronic circuit board at the same time.
In this case, the cylindrical plane is partially cylindrical.
Also in this case, the both sides are formed on a crossing tapered plane which are not orthogonal to the axis line.
Further in this case, the tapered plane is a circular cone plane.
In this case, the circular cone plane is a perfectly circular cone plane.
Also in this case, an outer circumference plane of each of the guides is cylindrical between the plurality of concave grooves.
In order to achieve still another aspect of the present invention, a mount shelf for an electronic circuit board, includes: peripheral walls; and four support bars supported on the peripheral walls in an inner space formed by the peripheral walls, and wherein the four support bars position and support four-point regions around edges of a rectangular electronic circuit board, and wherein a streamline plane in which air stream in a direction from two the support bars of the four support bars to the other two support bars is not turbulent is formed on the support bar.
In this case, an interference obstacle to a flow of the air stream flowing in the direction is not present except the four support bars.
Also in this case, the streamline plane is formed on a front side and a rear side of the air stream.
Further in this case, the four support bars have groove spaces for positioning the four-point regions, and wherein circumference of the groove space is formed on the streamline plane.
In this case, the streamline plane is formed symmetrically about the axis line of the support bar.